Printing devices such as laser printers, computer printers, facsimile machines, and copy machines are commonly used to print images on media. The media used is typically paper, but other media is often printed upon with a printing device. Further, images printed on media by printing devices are diverse, including text, photographs, graphics, and other data. Referring to FIG. 1, a block diagram of a typical printing device 100 is shown. The printing device may be a laser printer, ink cartridge printer, copy machine, or other device for printing images onto media. The printing device 100 typically includes three major sets of components: a print media feed 102, a marking engine 104, and a print media collector 106. Print media is supplied from the print media feed 102 to the marking engine 104, where information is printed onto the print media. After printing, the print media is moved into the print media collector 106. In many printing devices 100, the print media feed 102 includes at least one print media storage tray 108, 110, 112. In such printing devices, multiple print media storage trays 108, 110, 112 are provided to accommodate supplies of different sizes of print media, such as paper. The print media storage trays 108, 110, 112 and the marking engine 104 often are configured to move relative to one another to facilitate providing different sizes of print media to the marking engine 104. While three print media storage trays 108, 110, 112 are shown, different models of printing devices 100 use fewer trays or more trays. The print media feed 102 typically has a number of moving parts used to move print media into the marking engine 104. Adjacent to the first tray 108, a first print media feeder 114 pulls print media from the first print media storage tray 108 as needed, and supplies that print media to the marking engine 104. The first print media feeder 114 commonly includes one or more rollers. However, additional or different mechanisms are used as the first print media feeder 114 in different printing devices 100; for this reason the first print media feeder 114 is shown simply as a block in the block diagram. Similarly, adjacent to the second print media storage tray 110, a second print media feeder 116 pulls print media from the second print media storage tray 110 as needed, and supplies that print media to the marking engine 104. Adjacent to the third print media storage tray 112, a third print media feeder 118 pulls print media from the third print media storage tray 112 as needed, and supplies that print media to the marking engine 104. As with the first print media feeder 114, the second print media feeder 116 and the third print media feeder 118 are shown as simple representations of feeder mechanisms, and different mechanisms are used in different models of printing device 100.
Print media travels from the print media feed 102 along a print media path 137 through the marking engine 104. The marking engine 104 is typically an ink- or toner-based marking system. The marking engine 104 guides the print media along the path 137 such that images are printed upon it by a laser cartridge, an ink cartridge, an LED print head, an electrostatic print head, or another device by which images are printed on media. In the example shown, the print media path 137 travels through a first marking engine mechanism 120, a second marking engine mechanism 122, and a third marking engine mechanism 124. The marking engine mechanisms 120, 122, 124 guide print media along the print media path 137. The marking engine mechanisms 120, 122, 124 each commonly include one or more rollers. However, additional or different marking engine mechanisms 120, 122, 124 are used in different printing devices 100; for this reason the marking engine mechanisms 120, 122, 124 are shown simply as blocks in the block diagram. For example, one or more of the marking engine mechanisms 120, 122, 124 may be used for marking print media. More or fewer marking engine mechanisms 120, 122, 124 are used in different models of printing device 100 to move print media through the marking engine 104.
After the marking engine 104 prints onto the print media, that media is translated out of the marking engine 104 into the print media collector 106. The print media collector 106 generally includes at least one output tray 126, 128, 130. Multiple output trays 126, 128, 130 are typically included, providing for flexibility in print media output and handling. The output trays 126, 128, 130 and the marking engine 104 often are configured to move relative to one another to facilitate receiving print media in different output trays 126, 128, 130. While three output trays 126, 128, 130 are shown, different models of printing devices 100 use fewer outputs or more outputs. As an example, a printing device 100 that is a copy machine may have ten or more output trays to facilitate collation. The print media collector 106 typically has a number of moving parts used to receive print media from the marking engine 104. Adjacent to the first output tray 126, a first print media receiver 132 receives print media from the marking engine 104 and guides it into the first output tray 126. The first print media receiver 132 commonly includes one or more rollers. However, additional or different mechanisms are used as the first print media receiver 132 in different printing devices 100; for this reason the first print media receiver 132 is shown simply as a block in the block diagram. Similarly, adjacent to the second output tray 128, a second print media receiver 134 receives print media from the marking engine 104 and guides it into the second output tray 128. Adjacent to the third output tray 130, a third print media receiver 136 receives print media from the marking engine 104 and guides it into the third output tray 130. As with the first print media receiver 132, the second print media receiver 134 and the third print media receiver 136 are shown as simple representations of receiver mechanisms and different mechanisms are used in different models of printing machine 100. In some models of printing device 100, a single print media receiver 132 is used, which transfers the print media into a finishing device such as a stapler, hole puncher, or binding device. Such finishing devices are commonly utilized in business, industrial and government.
Typically all of the print media that passes through the printing device 100 is handled by all of the marking engine mechanisms 120, 122, 124. However, different print media feeders 114, 116, 118 are used to feed different sizes or types of print media into the marking engine 104. For example, when a single piece of print media is fed from the first tray 108 into the marking engine 104 by the first print media feeder 114, the second print media feeder 116 and the third print media feeder 118 are idle. Thus, the print media feeder associated with a print media storage tray containing a commonly-used print media size or type is utilized more often than the print media feeders associated with print media storage trays containing less-frequently used print media sizes or types. Similarly, different print media receivers 132, 134, 136 may be used to receive different units of print media from the marking engine 104. For example, when a sheet of print media is received from the marking engine 104 into the first print media receiver 132, the second print media receiver 134 and the third print media receiver 136 are idle. Thus, the print media receiver associated with a particular output tray typically is utilized more often than the other print media receivers. For example, most print jobs only require the delivery of a single copy of the print job into a default output tray, so the other output trays and their associated print media receivers are used less frequently. Table 1 illustrates the differential use of discrete print media path components with an example, in which 56,000 individual sheets of paper have been printed using the printing device 100.
TABLE 1Example of Differential Use of DiscretePrint Media Path ComponentsDiscrete Print Media Path ComponentIndividual Sheets ProcessedFirst Print Media Feeder 11440,000Second Print Media Feeder 116 6,000Third Print Media Feeder 11810,000Marking Engine Mechanisms 120, 122, 12456,000First Print Media Receiver 13255,000Second Print Media Receiver 134  500Third Print Media Receiver 136  500
In this example, the first print media feeder 114 is used in conjunction with a commonly-used paper size such as 8½×11 inch paper, placed in the first print media tray 108. The other two print media trays 110, 112 contain paper sizes used less frequently, reflected in the corresponding lesser use of the second print media feeder 116 and the third print media feeder 118. Each of the 56,000 individual sheets that moves through the printing device 100 passes through each of the marking engine mechanisms 120, 122, 124. The first print media receiver 132 corresponds to the default print media output tray 126, such that it receives most of the paper output from the marking engine mechanisms 120, 122, 124. The second print media output tray 128 and the third print media output tray 130 are used less frequently, reflected in the corresponding lesser use of the second print media receiver 134 and the third print media receiver 136.
Different discrete components used to handle print media within the printing device 100 wear at differential rates, because some discrete components encounter heavier usage than others. The discrete components within the printing device 100 typically require periodic replacement due to wear. Such discrete components include the print media feeders 114, 116, 118, the marking engine mechanisms 120, 122, 124, and the print media receivers 132, 134, 136. Other moving parts in the print media path 137 used in addition to or instead of those parts may need periodic replacement as well. Wear is typically measured by counting and recording the number of units of print media that are processed through the printing device 100. A formatter 150 typically performs such counting and recording.
The formatter 150 may be an integrated circuit, a portion of an integrated circuit, a processor, or any other structure or combination of structure and software adapted to monitor the number of uses of each discrete component. The formatter 150 is connected via wiring or via a wireless connection to the print media feed 102, marking engine 104, and print media collector 106, such that the formatter 150 can control these components. The print media feed 102, marking engine 104 and the print media collector 106 each include standard wiring, motors, and other electrical and mechanical components used for actuation, control, and printing. The particular configuration of the electrical and mechanical components within the print media feed 102, marking engine 104 and the print media collector 106 are not critical to the invention.
The particular format of the digital input received by the formatter 150 varies among printing devices 100. The content of that digital input typically includes information, separated by page, relating to the image to be placed onto each particular sheet of print media. A logical signal or set of signals is associated with each page. Thus, the digital input is formatted and printed correctly on a sheet-by-sheet basis. By counting each received logical signal, or set of logical signals, associated with a single unit of print media, the formatter 150 counts the number of individual units of print media printed upon by the printing device 100, and stores the count within the formatter 150 or an associated memory device. In other printing devices 100, a sensor is used to physically sense individual units of print media printed upon in the printing device 100.
In one embodiment, a display 142 is connected to the formatter 150. The display 142 may be a liquid crystal display (LCD), one or more light-emitting diodes (LEDs), or any other device capable of displaying information to a user. The formatter 150 is also connected to a communications interface 152, which may be a modem, a network interface card, or any other device that allows the formatter 150 to communicate with an external device. Digital input is received into the formatter 150 via the communications interface 152, and output may be transmitted through the communications interface 152 from the formatter 150.
Typically, after the formatter 150 records a particular number of units of print media as having been printed upon, a display 142 or other alert on the printing device 100 is activated, indicating that service is required. The formatter 150 does not record the actual usage of individual print media path components. Instead, it simply counts and records the number of units of print media processed through the printing device 100. Replacement intervals for print media path components typically are based on the recorded number of processed pages. However, as described above, while all discrete print media path components are subject to wear, not every component is used for each page processed. Therefore, at a particular replacement interval, print media path components may be replaced that do not need to be replaced. For example, after a particular page count has been reached, all of the print media path components are typically replaced, including the print media feeders 114, 116, 118, is the marking engine mechanisms 120, 122, 124, and the print media receivers 132, 134, 136 are all replaced. However, some of those replaced components may have useful life remaining. Their premature replacement results in additional cost and maintenance time.